1. Field of the Invention
The present invention relates to a laminated plate for a high frequency and usable as, for example, electrical circuit substrates and a flat antenna.
2. Description of the Related Art
As a laminated plate for a high frequency to be used as a high frequency electrical circuit substrate a copper-laminated plate, comprising copper laminated by bonding to the outermost layer of a laminate having a prepreg impregnated with a resin laminated to reinforcing fibers such as glass fibers, has been used. As the resin material for such a laminated plate for a high frequency, a poly(4-methyl-1-pentene) has been proposed (Japanese Unexamined Patent Publication (Kokai) No. 58-46691). Poly(4-methyl-1-pentene) has excellent high frequency characteristics, such as a dielectric constant and dielectric loss, in the gigahertz zone, and thus is most appropriate for use as the resin material of a laminated plate for a high frequency.
Nevertheless, in such a prior art laminated plate for a high frequency, which employs poly(4-methyl-1-pentene) as such, impregnation of the reinforcing fibers is difficult, and therefore, the resin must be impregnated as a solution dissolved in a solvent, or laminated in a powdery form and then impregnated by heating and melting. When using a solvent, the process is dangerous and the workability is poor, and when impregnating in a powdery form, a problem arises in that it is difficult to effect a uniform impregnation. Also, poly(4-methyl-1-pentene) has a poor adhesiveness, and thus another problem arises in that an adhesive must be used for attaching a copper foil.